Root Cellar
A modest stepdown root cellar off a pantry.
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Food storage is an essential component of rural survival. Enough
food for one winter per person is a good start and work up to storing
one years worth. Ideally we want to grow as much food as possible
and buy or trade in bulk for the rest. However all that food will
become spoiled and useless in a short time if not stored properly.
The main concern is temperature, the food cannot be allowed to freeze
or reach room temperature.
Most food out of a garden will not keep unless canned, dried or
frozen. The natural keepers like potatoes, onion, garlic and winter
squash will last through most of the winter if kept in a consistently
cool, dark and dry environment. Dried food like sacks of grain,
nuts or dried fruit are more forgiving but they too will last longer
under those conditions. What we need is a root cellar.
Root cellars are the traditional food storage structures, called
as such because they were dug into the ground or bermed up with
earth to approximate a cave for temperature control. Deep caves
have a steady temperature year around, independent of the air temperature
outside whether a deep freeze or a withering heat wave.
Root cellars can be built below the house, in the basement, outside
as a stand alone structure or even as just a closed off area of
the house itself. The main concern being insulation from the surrounding
air temperature. Food is best kept in a dark, dry and consistently
cool area.
The pictures shown are of a modest root cellar built into the north
side of a house. It's a step down room about four feet below floor
level with a cement floor and knee wall bermed up with earth on
the outside. Above the knee wall and interior walls are about a
foot thick and insulated. It has two small windows for light and
venting. It works well as food and homemade wine storage for two
people. Note the thermometer on the wall for temperature monitoring.
Cement floor root cellar on the north side of
the house with earth berm insulation. |
About 100 sq.' in size.
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Small window for light and vent.
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An interesting fact is that a root cellar with an insulated floor
is more apt to freeze in extreme low temperatures than an uninsulated
floor such as plain dirt or cement. The reason being the earth itself
gives off constant heat which may not seem like much but when the
air temperature is zero, constant 40 F degrees is warm by comparison.
When insulation cuts off that warmth freezing can occur.
Burying an ocean going container
maybe the fastest way of having a root cellar that is secure and
bug proof. Even a partial burial with enough earth berm thickness
on the sides and a mound on top would work. Another alternative
which maybe more cost effective is to enclose the container with
a straw bale shell, similar to building a straw bale house except
with the container serving as the frame. Cost effective in the fact
that the bales of straw would be cheaper to buy and have delivered
than hiring a backhoe or an excavating machine to dig a big hole,
devise a drainage system and placing the container in it. However
a free standing, above ground straw bale root cellar is the way
to go as the least expensive choice. If I did not have a container,
that would be my choice.
20' container planned for a root cellar.
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Bales of straw are stacked like interlocking bricks against exterior
surfaces with steel rebars rammed through the bales to add stability.
The bottom row would be off the ground and the outer surfaces sprayed
with plaster or stucco for weather and bug proofing. A roof, even
a flat one, can be laid right on top without snow load worries.
Ideally the doors would face north with some sort of an airlock
or a thresh hold entrance so hot outside air during summer will
not rush in when opened.
Big straw bale in field. |
Straw close up. |
Straw should not have leaf or seeds. |
Average straw bales in our region measure 18"Wx14"Hx36"L
and weigh about 35lbs. and cost $1.50 to $4 a bale at a feed store,
the price fluctuating on the growing and harvesting weather. Approximately
200 bales are needed to cover a 20' ocean container. Buying in quantity
from a farmer directly should lower the price.
Depending on how the straw is baled, the R or the insulation value
is close to R2 per inch or R36 for a 18" wide straw bale with
about a 3.5 sq' coverage on the 14"x36" side. By comparison
fiberglass insulation of R38 is 12" thick with a unit coverage
of 32 sq' at roughly $1.00 sq'.
The big disadvantage of fiberglass insulation is that it requires
a frame to hang it in. Any thickness beyond 6" and the lumber
required becomes cost prohibitive and any sort of double wall construction
would be tricky and time consuming. Foam is the most expensive of
insulating materials and also require some sort of frame to set
it in.
If I were to build a house, I would choose the straw bale construction.
I plan on using straw bales to convert my container to an above
ground root cellar and also to insulate a large above ground water
storage tank.
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